Does every woman require a post-lumpectomy mammogram and ultrasound before radiotherapy when negative margins?

Abstract

PurposeMost studies regarding the value of post lumpectomy imaging (PLI) studies rely on mammography alone and are often focused on patients that present with suspicious microcalcifications or in situ disease. This way, its true benefit remains controversial, which explained the heterogeneity between centers. This is the first study to evaluate the role of mammography with breast and axillary ultrasound undertaken before radiotherapy in patients with conservatively managed invasive and/or in situ carcinoma with negative margins. Materials and MethodsIn this retrospective study, medical records for patients referred to our External Radiotherapy Unit between January 2018 and December 2019 were reviewed. ResultsA total of 1251 patients (1262 breasts) were analyzed. A total of 3.4% had suspicious findings for local residual breast disease, with 1.0% having a re-excision positive for residual malignancy. Presentation with microcalcifications alone (OR=4.854), extension of microcalcifications>3cm (OR=13.500), histologic subtype pure ductal carcinoma in situ (OR=12.348), presence of invasive carcinoma≤1mm of the pathological margins (OR=4.630), stage pTis (5.630), and absence of invasive component (OR=4.629), were associated with an increased risk for residual malignancy. Only one patient (0.1%) had nodal residual involvement. ConclusionPLI detected residual local cancer in 1.0% of the patients. PLI plays an important role in the evaluation of patients undergoing breast-conserving therapy with negative margins. The major question that remains is whether it changes survival outcomes.